HTTP 103 Early Hints vs 425 Too Early
HTTP 103 (Early Hints) is a 1xx Informational response, while 425 (Too Early) is a 4xx Client Error response. 103 indicates that used to return some response headers before the final HTTP message. Allows the browser to start preloading resources while the server prepares the response. In contrast, 425 means that the server is unwilling to risk processing a request that might be replayed. Used with TLS 1.3 early data (0-RTT).
Description
Used to return some response headers before the final HTTP message. Allows the browser to start preloading resources while the server prepares the response.
When You See It
When a server wants the browser to start loading CSS/JS before the full response is ready.
How to Fix
No fix needed. This optimization helps speed up page loading.
Description
The server is unwilling to risk processing a request that might be replayed. Used with TLS 1.3 early data (0-RTT).
When You See It
When a server rejects a request sent as TLS 1.3 early data due to replay risk.
How to Fix
Retry the request after the TLS handshake completes.
Key Differences
103 is a 1xx Informational response, while 425 is a 4xx Client Error response.
HTTP 103: Used to return some response headers before the final HTTP message. Allows the browser to start preloading resources while the server prepares the response.
HTTP 425: The server is unwilling to risk processing a request that might be replayed. Used with TLS 1.3 early data (0-RTT).
You encounter 103 when when a server wants the browser to start loading CSS/JS before the full response is ready.
You encounter 425 when when a server rejects a request sent as TLS 1.3 early data due to replay risk.
When to Use Which
For 103 (Early Hints): No fix needed. This optimization helps speed up page loading. For 425 (Too Early): Retry the request after the TLS handshake completes.